下列反应在任意温度下一定能自发进行的是( )A.2NaCl+2H2O 电解 . 2NaOH+Cl2↑+H2↑B.NH3(g)+HCl(g)═NH4Cl(s)△H<0C.CaCO3(s)═CaO(s)+CO2(g)△H>0D.X2Y2(s)═X2(g)+Y2(g)△H<0